High-quality training focused on substance abuse epidemiology is needed to prepare talented young scientists committed to a career in substance abuse epidemiology to become the next generation of leaders in this field. Accordingly, this proposal for T32DA031099 (revised) describes a new pre- and postdoctoral substance abuse epidemiology training program located in the Department of Epidemiology, Mailman School of Public Health (MSPH), at Columbia University (CU), in collaboration with the Department of Psychiatry, College of Physicians and Surgeons. The Departments of Epidemiology and Psychiatry are both rich training environments, providing an outstanding setting for a CU program uniquely dedicated to the specialized training necessary for careers in substance abuse epidemiology. The program takes a cells-to-society perspective on substance abuse epidemiology, and will offer training at multiple levels of causation, ranging from the molecular t large-scale social forces. Training will provide fellows with broad yet intensive training in the field of substance abuse epidemiology and related areas, depth in an area of specialization; a set of methodological and conceptual skills, including formulation of key research questions and testable hypotheses, and the design and conduct of high-quality substance abuse epidemiology studies to test those hypotheses. Fellows will also learn to present their findings in professional contexts, to publish peer-reviewed manuscripts and write fundable grant proposals; to collaborate with others, and to receive training in the responsible conduct of research. This will be accomplished through academic courses at MSPH including a two-semester substance abuse epidemiology core sequence; a weekly faculty-fellow seminar in substance abuse epidemiology; mentoring and co-mentoring; field placements; opportunities for presentations; instruction and supervision in the preparation of manuscripts and grant proposals; other activities, e.g., Grand Rounds, leadership workshops, interaction with other training programs; and training in the responsible conduct of research. The program will begin with slots for 2 predoctoral fellows (Ph.D. candidates in epidemiology), and 2 postdoctoral fellows from relevant disciplines in Years 01 and 02, increasing to 3 and 3 in Year 03, following NIDA recommendations. The 25 internationally recognized faculty members have very strong track records in publishing, funding, and mentoring successful trainees. Trainees will be selected based on their interest in and commitment to substance abuse epidemiology, their prior accomplishments, and experience. Intensive recruitment efforts will be made to enroll and retain trainees from under-represented groups. The proposed training program will have a rigorous evaluation plan, including process and outcome measures.